linux-kernel - Re: [PATCH] xfs: Fix 64-bit division on 32-bit in xlog_state_switch

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Message-ID: <20210610225026.GD2945738@locust>
Date:   Thu, 10 Jun 2021 15:50:26 -0700
From:   "Darrick J. Wong" <djwong@...nel.org>
To:     Dave Chinner <david@...morbit.com>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Dave Chinner <dchinner@...hat.com>,
        Chandan Babu R <chandanrlinux@...il.com>,
        Allison Henderson <allison.henderson@...cle.com>,
        Christoph Hellwig <hch@....de>, linux-xfs@...r.kernel.org,
        linux-next@...r.kernel.org, linux-kernel@...r.kernel.org,
        noreply@...erman.id.au
Subject: Re: [PATCH] xfs: Fix 64-bit division on 32-bit in
 xlog_state_switch_iclogs()

On Fri, Jun 11, 2021 at 08:01:55AM +1000, Dave Chinner wrote:
> On Thu, Jun 10, 2021 at 01:00:01PM +0200, Geert Uytterhoeven wrote:
> > On 32-bit (e.g. m68k):
> > 
> >     ERROR: modpost: "__udivdi3" [fs/xfs/xfs.ko] undefined!
> > 
> > Fix this by using a uint32_t intermediate, like before.
> > 
> > Reported-by: noreply@...erman.id.au
> > Fixes: 7660a5b48fbef958 ("xfs: log stripe roundoff is a property of the log")
> > Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
> > ---
> > Compile-tested only.
> > ---
> >  fs/xfs/xfs_log.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> <sigh>
> 
> 64 bit division on 32 bit platforms is still a problem in this day
> and age?
> 
> Reviewed-by: Dave Chinner <dchinner@...hat.com>
> 
> Maybe we should just put "requires 64 bit kernel" on XFS these days...

But then how will I recover my 100TB XFS using my TV?  It only has so
much framebuffer that I can abuse for swap memory...  >:O

Reviewed-by: Darrick J. Wong <djwong@...nel.org>

--D

> 
> -Dave.
> -- 
> Dave Chinner
> david@...morbit.com